Inverse Hartmann Surface Form Measurement Based on Spherical Coordinates

Various methods for surface form measurement of aspheric and complex optics exist at present. Each method is just suitable for several limited optic surface form measurement. Hartmann measurement is a method that reconstructs the surface form of a test mirror from form slope. It gives quantitative evaluation of a test mirror in a short time. Compared with interferometry, it has advantages such as relatively simple setup, good anti-disturbance property and low cost. However, it is difficult for conventional Hartmann and Shack-Hartmann methods to increase their measurement dynamic range and resolution simultaneously, and they can not be used to measure steep aspheric surface form. A novel method named inverse Hartmann surface form measurement based on spherical coordinates is presented. The method increases the measurement dynamic range and resolution simultaneously. It reduces the measured ray slope, increases the measurement range, and its accuracy of form error is higher than that in rectangular coordinates. It can be applied in online optic product evaluation rapidly and accurately with low cost.